STUDIES ON VERATRUM ALKALOIDS

VII. Receptor Areas in the Coronary Arteries and Elsewhere as Revealed by the Use of Veratridine

¹ Department of Pharmacology, Harvard Medical School, Boston, Massachusetts

The sites of the cardio-vascular and respiratory actions of small doses of veratridine have been localized by injection into the various cavities of the heart, great vessels and coronary arteries of cats and dogs.

1. By far the greatest part of the reflex fall of blood pressure and heart rate on injection of veratridine originates from the area supplied by the left circumflex and left anterior descending coronary arteries, i.e. the left ventricle. This action of veratridine is increased by the simultaneous injection of sodium citrate and is reduced by calcium chloride.

2. Injection of veratridine into the perfused left lung also causes a fall of blood pressure and heart rate; this area is more than ten times less sensitive than the left ventricle.

3. Veratridine causes a reflex depression of the rate and depth of respiration, originating from the lungs and abolished by vagotomy. In larger doses it causes a similar depression by a direct action on the central nervous system; this is not affected by vagotomy.

4. Injection of veratridine into the perfused carotid sinuses has no effect on circulation or respiration.

5. Veratridine potentiates the action of potassium chloride on the central nervous system in causing a fall of blood pressure and heart rate, and a reduction in the rate and depth of respiration.

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